i think the thing you are looking for is just called a presentation portfolio or presentation book...
i have a really cheap one i got at an office supply store, but it doesn't have a brand name on it ...
if the local office supply store doesn't have them have you tried going online to the mothership
to see if they just don't carry them locally ? they might be able to ship directly to your store
so you don't have to pay shipping
good luck !